1. Field of the Invention
The present invention relates to an imaging device and an imaging system, and more particularly relates to an imaging device and an imaging system having a light-sensing pixel region and a light-shielded pixel region.
2. Description of the Related Art
There are known imaging devices which have a light-sensing pixel region and a light-shielded pixel region. Japanese Patent Laid-Open No. 2010-267675 discloses an imaging device having a light-sensing pixel region, an invalid pixel region located on the outer side of the light-sensing pixel regions, and an optical black region (OPB region) located on the outer side of the invalid pixel region. Above the light-sensing pixel region, invalid pixel region, and OPB region, are formed wiring layers 1MT and 2MT. The wiring layers 1MT and 2MT have openings formed corresponding to photodiodes of individual pixels. Wiring layers 3MT and 4MT, which are formed further above the wiring layers 1MT and 2MT disposed above the light-sensing pixel region and invalid pixel region, are disposed above the OPB region, such that the wiring layers 3MT and 4MT shield incident light to the OPB region.
The imaging device disclosed in Japanese Patent Laid-Open No. 2010-267675 has openings formed in the wiring layers 1MT and 2MT formed above the light-sensing pixel region and invalid pixel region, at positions above the OPB region in the same way as for the light-sensing pixel region and invalid pixel region. Accordingly, at an OPB region adjacent to an invalid pixel region in particular, light diagonally input from the invalid pixel region toward the direction of the OPB region readily enters the OPB region. When light is entering the OPB region, signals when light is shielded (noise signals) cannot be correctly detected, so it becomes difficult to obtain accurate image signals. Also, it is desirable to reduce the optical path difference regarding incident light to each pixel in the light-sensing pixel regions, and to suppress unevenness in color, in order to obtain more accurate image signals.